One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,7)(3,6,8,4)(9,10,14,16)(11,12,18,20)(13,15,23,22)(17,19,21,24)(28,36)(32,39)(35,37)(38,40)(1,3)(2,4)(5,8)(6,7)(9,11)(10,12)(13,21)(14,18)(15,24)(16,20)(17,23)(19,22)(25,26)(27,34)(28,32)(29,31)(30,33)(35,40)(36,39)(37,38) involution — undirected(1,2)(3,4)(5,7)(6,8)(9,12,14,20)(10,11,16,18)(13,19,23,24)(15,17,22,21)(25,27,30,29)(26,31,33,34)(28,35,36,37)(32,38,39,40)(1,3)(2,6)(4,7)(5,8)(9,12)(10,11)(13,19)(14,20)(15,17)(16,18)(21,22)(23,24)(25,28)(26,32)(27,35)(29,37)(30,36)(31,38)(33,39)(34,40) involution — undirected(1,4,5,6)(2,3,7,8)(9,13)(10,15)(11,17)(12,19)(14,23)(16,22)(18,21)(20,24)(25,26)(27,31)(28,32)(29,34)(30,33)(35,38)(36,39)(37,40)(1,3)(2,4)(5,8)(6,7)(9,10)(11,12)(13,22)(14,16)(15,23)(17,24)(18,20)(19,21)(25,29,30,27)(26,31,33,34)(28,37,36,35)(32,38,39,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.